Motion picture projector

ABSTRACT

A motion picture projector having a fixed relation of the film transport operating mechanism to the shutter operating means and operating at a normal mode or rate of operation such as to produce continuous motion pictures, control apparatus is provided to alter or change the mode or rate of operation from a normal continuous projection speed to a &#39;&#39;&#39;&#39;sequence&#39;&#39;&#39;&#39; of motion picture projection, i.e., a slow series of automatically changing still projections, and to produce by stepless, i.e., continuous, increments a change in the intervals of the still projections in any such automatically changing series of still projections. Such changes in the mode or rate of operation is effected without altering the fixed relation between the film transport operating mechanism and the shutter operating mechanism.

ijriited States Patent 1 Kotler et a1.

[111 3,746,441 July 17,1 73

1 1 MOTION PICTURE PROJECTOR [73] Assignee: DeJur-Amsco Corporation,Long Island City, NY.

[22] Filed: Jan. 21, 1972 [21] Appl. No.: 219,744

[56] References Cited UNITED STATES PATENTS 3,524,573 8/1970 Kotler226/122 X 3,603,678 9/1971 Anderl 352/177 X 3,520,596 7/1970 O'Donnell352/169 X 3,591,265 7/1971 Shropshire 352/169 X 3,637,125 1/1972Freudenschuss... 226/62 3,671,113 6/1972 Johnson 226/62 X PrimaryExaminer--Samuel S. Matthews Assistant Examiner-Monroe 1-1. HayesAttorney-Maxwell James et al.

[57] ABSTRACT A motion picture projector having a fixed relation of thefilm transport operating mechanism to the shutter operating means andoperating at a normal mode or rate of operation such as to producecontinuous motion pictures, control apparatus is provided to alter orchange the mode or rate of operation from a normal continuous projectionspeed to a sequence" of motion picture projection, i.e., a slow seriesof automatically changing still projections, and to produce by stepless,i.e., continuous, increments a change in the intervals of the stillprojections in any such automatically changing series of stillprojections. Such changes in the mode or rate of operation is effectedwithout altering the fixed relation between the film transport operatingmechanism and the shutter operating mechanism.

10 Claims, 8 Drawing Figures PAIENIED U 7W5 SHEET 7 BF 7 MOTION PICTUREPROJECTOR This invention relates to a motion picture projector and moreparticularly to a motion picture projector embodying controls foraltering or changing the mode, i.e., the rate of projection of themotion pictures from a normal or continuous projection to (a) a sequenceof picture projection, i.e., a slow series of automatically changingstill projections and (b) for changing by stepless or continuousincrements the intervals of the still projections in any suchautomatically changing series of still projections.

In conventional projectors of the motion picture type, provision isoften made to stop the projection so as to render a still picture. Insome projectors provision is made to project the image at slow motion,as by transporting the film one frame every other stroke of the filmtransport means. In other projectors the rate of projection is slowed byreducing the speed of the motor. In still other projectors slower speedsare obtained by combining slow motion and slowing the drive motor. Theslowness of projection speed is limited by the introduction ofobjectionable flicker.

In a motion picture projector having a fixed relation of the filmtransport operating means to the shutter operating means and operatingat a normal rate such as to produce continuous motion pictures, it isdesirable to alter or change the mode of operation such that the rate ofprojection is slowed down so as to produce the effect of a sequenceprojection or a series of still projections. Sequence projection in thiscontext may be defined as a speed slower than slow motion projection orslow projection speed. If, for example, slow projection is made at therate of say, six frames per second, then sequence projection is definedas any speed less than six frames per second. It is thus desirable tochange the rate of projection to any rate slower than six frames persecond in increments so as to produce a series of automatically changingstill projections, as well as to vary rate of change, namely theintervals or time spacing of the still projections in stepless, i.e.,continuous increments in any such automatically changing series of stillprojections. It is also desirable to effect I these projection ratechanges without changing the shutter speed and hence without introducingobjectionable flicker. It is also desirable to provide for theproduction of unchanging still projections, namely projection of stills,for indeterminate periods.

It is the prime object of the present invention to produce a motionpicture apparatus embodying controls for effecting the changes in themodes or rates of projection of the motion pictures in the ways abovedescribed, and also a control compatible therewith for producingunchanging still projections,

To the accomplishment of the foregoing objects and such other objects asmay hereinafter appear, our invention is directed to the motion pictureprojector as FIG. 3 is a rear elevational view of the parts of theprojector shown in FIG. 1;

FIG. 4 is a rear elevational view of the parts of the projector of FIG.1 taken in cross section along the broken lines 4-4 of FIG. 3;

FIG. 5 is a side elevational view of parts of the projector shown inFIG. 1 viewed in the direction of the line 55 of FIG. 1;

FIG. 6 is a schematic view of the electronic circuit mechanism forselectively changing the mode or rate of picture projection of thepresent invention; and

FIGS. 7a and 7b are composite views depicting the graphicalrepresentation of the electronic circuit system of FIG. 6 and depictingthe effects of the operation of the mechanism for selectively changingthe mode or rate of picture projection.

Referring now more in detail to the drawings, we shall first describethe structure and operation of the motion picture projector shown inFIGS. 1 to 5 of the drawings. These figures show an embodiment of thesalient mechanical parts of the projector disclosed in U. S. Pat. No.3,524,573 patented Aug. I8, 1970 (of which one of the applicants was aco-inventor) modified for adaption to and the incorporation of theelectronic system shown in FIGS. 6 and 7a and 7b of the presentdisclosure. For identification, the salient parts of the projector asshown in FIGS. 1 to 5 hereof will have applied thereto the samereference characters as applied to the corresponding parts of theprojector disclosed in said US. Pat. No. 3,524,573.

In this projector, power is obtained from a source through a suitabletransmission (not shown) delivered to the main drive shaft 1 by a drivebelt 2 connected to a compound pulley 3 affixed to the shaft 1. Shaft 1rotates in a bearing 4 which is mounted in the main support structure 5of the projector. A shutter blade 6 is affixed directly to the compoundpulley 3.

The projector is characterized by the provision of a film transportmeans which for its film perforation penetration is activated by aspring biased means, employed in conjunction with a cam operated meansoperable at a predetermined normal cyclic speed and which cam operatedmeans is active on the transport means in opposition to saidspring-biased means for effecting an outward movement of the transportmeans for film perforation disengagement for each transport cycle. Suchfilm transport means comprises a cam 7 affixed to the main shaft 1,which cam rotates between shoes 8 and 9 acting as cam followers, whichshoes form part of a film transport means 10. Said cam is operable inboth clockwise and counterclockwise modes. Film transport means I0 ispivotally movable about a retainer 11, which latter comprises apositional bearing serving both as a pivot about which the filmtransport means 10 oscillates and as a confining element such thatslidable in and out motion of the film transport is permitted.

Pin 13 is eccentrically positioned with respect to a control shaft I4,which latter is rotatably mounted in a bearing 15 held in a frame plateI6. A manually operable knob 17 is keyed to the control shaft I4. Aspring I8 located around an extension of the pin I3 applies pressureagainst the retainer II. A change of angular position of the pin 13 withrelation to the shaft 14 and the cam 7 has the effect of shifting thefulcrum about which the film transport means 10 oscillates andtranslates, thus changing the points of penetration of the filmperforations by the claw (hereinafter referred to) of the film transportmeans for framing the film in the projector. In the accompanyingdrawings as shown particularly in FIG. 1 thereof, the film transportmeans is shown in mid-position of its return or up stroke movement whencam 7 rotates clockwise in the forward mode. Conversely, theillustration in the drawings may also be viewed with the cam 7 operatingin the reverse mode (counter-clockwise) thus illustrating the positionof the film transport means in mid-position in the down stroke.

Penetration of film perforation by the film transport means iscontrolled by a first cam 20 which is affixed to or made integral withcam 7 (the pull-down cam) and thus operates at the aforesaid determinedcyclic speed. The film transport means 10 is formed with an armextension 21 which engages the peripheral surface of the cam 20 servingas the cam follower.

The spring-biased means which is active on the film transport means toeffect an inward translatory movement thereof for film perforationcomprises a torsion spring 22 active at one end on the end of the filmtransport means 10, as clearly depicted in FIGS. 1 and 2 of thedrawings, exerting pressure thereon in a generally longitudinaldirection through the center pin 13 and the main shaft 1. A stop 23 (seeFIG. 1) is a fixed element holding the other end of the spring 22 in agenerally constant position. The pull-down cam 7 is maintained in alateral position by means of a guide 24 such that oscillatory andtranslatory motion of the film transport means is permitted, the saidguide being affixed to the main support structure by means of the bolt25.

By means of this described structure the film transport means isactivated by a spring-biased means (the spring 22) which is active onthe film transport means 10 to effect an inward translatory movementthereof for film perforation penetration and there is thus provided alsoa first cam operable at a predetermined cyclic speed with means operableby said first cam at said cyclic speed and active on the transport meansin opposition to said spring-biased means for effecting an outwardtranslatory movement of the transport means for film perforationdisengagement for each film transport cycle.

For adapting these described parts of the projector for the selectivechange mode operations referred to, the film transport means 10 isprovided with a pin 26 affixed thereto, the pin projecting through asuitable aperture 27 in the main support structure 5. The pin 26 engagesin a cooperating slot 28 in a slide member 29, the slide member beingprovided with a laterally extending arm 30. The slide member is formedwith bearing slots 31 and 32 through which bushings 33 and 34respectively extend, said bushings being retained in place againstsuitable surfaces of the main support 5 by screws 35, 35. The fitbetween the slide member 29 and the bushings are such as to permit free,translating motion of the slide member when driven by the film transportmeans 10. The film transport means is formed at its film penetrating endwith the claw 36.

For cooperation with the slide member 29 there is provided a solenoid 37secured to a bracket 38 by means of a nut 39. The bracket is in turnattached to the main support of the projector. The solenoid has anarmature 40 to which a shoe 41 is secured. A ring 42 is secured to thearmature 40 spaced by a non-metallic washer 43. A pin 44 is affixed tothe shoe 41, the said pin extending through a slot 45 in the bracket 38such that the pin 44 is slidable in said slot. With this constructionwhen the solenoid 37 is de-energized, the armature 40, the pin 44, thering 42 and washer 43 are driven in a downward direction under theaction of a spring 46 to a solenoid deenergized position which is areset position. Downward motion is limited by the position of the lowerend of the slot 45. FIGS. 1 and 3 depict this reset position of theparts. In such position the shoe 4] (as will be detailed morehereinafter) is interposed to engage the arm 30 of the slide member 29to prevent the further movement of said arm and the film transport meansattached thereto into a film penetrating position; these positions ofthe parts are also clearly indicated in FIGS. 1 and 3 of the drawings.The spring 46 is anchored to the bracket 38 by the means 47.

The described projector is further provided with a commutator 48 fixedto the main shaft 1, the said commutator having two annular grooves 49and 50 (see particularly FIGS. 3 and 4) and an electrically conductivepin 51 extending through said annular grooves. The commutator and itspin are thus in fixed relation to the cams 20 and 7.

Electrically conductive springs 52 and 53 are affixed to a mount 54 atattachments 55 and 56 respectively to which two lead wires 57 and 58respectively are connected, these lead wires being in turn connected tothe electronic system as will be described further hereinbelow. Themount 54 is suitably attached to the main support 5 by the bracket 59. Acap 60 is provided to serve as a protective cover for the conductivesprings 52 and 53. The lead wires are in a normally open state duringeach rotation of the main shaft except when momen tary contact iscreated by the pin 51 contacting the conductive springs 52 and 53.

When the projector is operating, claw 39 is driven so as to produce afilm transporting motion. Penetration and depenetration of the filmperfortions is controlled by cam 20 acting in conjunction with cam 7which latter controls the vertical transport of the film. Thepenetration stroke of claw 39 is controlled, in part, by the armextension 21 of the film transport means which follows the surface ofthe cam 20, under the force exerted by tension spring 22. It can thus beseen that lateral film penetration movement of the film transport means10 and the slide 29 are restricted if and when shoe 411 of the solenoidassembly is in the de-energized, or down, position. When this occurs,extension arm 30 of slide 29 strikes the bottom of shoe 41 thus limitingmotion of the claw 39 in the direction of the film. Penetration of thefilm by the claw is thus prevented and film transport does not occur.When film penetration is prevented as described, the arm 21 of filmtransport means 10 loses contact with the surface of cam 20 for aportion of the rotation of said cam. When solenoid 37 is energized themotion of claw 39 and slide 29 are unrestricted and normal filmtransport occurs in either its forward or reverse modes.

When solenoid 37 connected to the electronic circuit system to bedescribed below, receives an electrical pulse of short duration, saidsolenoid will be energized for a correspondingly short interval of time,sufficient to cause the solenoid armature assembly (40 to 44) to strokeup and down for an interval of less than one period of rotation of thecams 20 and 7, determined by the time of contact of contact springs 52and 53 with the armature pin 51.

When solenoid 37 is de-energized, the said armature assembly is drivendownward to a reset position by the influence of spring 46. Upwardmotion is limited by washer 43 striking an extension 62 of the solenoid37. Completion of the reset stroke of the armature assem' bly occurswhen extension arm 30 of slide 29 is retracted from the path of saidarmature assembly by the depenetration stroke of the surface of the cam20. Further film transport cannot occur until solenoid 37 isreenergized.

It can be seen therefore, that when the solenoid is energized forrelatively long periods of time, the effect will be that of normalmotion picture projection. On the other hand, when the solenoid receivesan electrical pulse, the effect will be to change the frames beingprojected to the next adjacent frame. The new frame now being projectedwill remain until the next succeeding pulse.

Still" projection for an indeterminate period is obtained by theprovision of a manually controlled element which is selectively movableinto the transport path of the transport means to intercept the inwardtranslatory movement thereof to inhibit its engagement with the cam 20,thereby preventing or inhibiting film penetration. This element may beheld in such intercepting position for any desired period. Thisoperation is secured by manually interposing the left end fingers 63 ofa lever 64 into the arm 65 of transport means 10. Its function issimilar to that of the extension arm 21 of the transport means so thatthe claw 36 is thereby prevented from entering the film perforations,and thereby preventing the film from being transported. This still modeof operation may take place over an indefinite period of time.

The lever 64 is pivotable about the stud 66 (see FIG. 2). A projectingarm 67 of this lever is an anchor for one end of a spring 68, and aprojecting lug 69 on a rotatable member 70 is an anchor for the otherend of the spring 68. The spring functions as an overcenter detent andmaintains the lever 64 in position at either end of its stroke. Motionis manually imparted to the lever by means of a suitable knob 70'attached to the member 70. FIG. 2 illustrates the still mechanism in itsdisengaged position. It will be seen that the operation of this manualcontrol of the transport means is com; patible with the operation of theslide member 29 so that the production of stills may be obtainedindependent of the operation of the projector by way of the solenoid 37.a

FIG. 6 of the drawings depicts the circuitry and the electronic circuitsystem for operating the solenoid 37 to produce the different rates ormodes of picture projection embodying the principles of the invention.

In its generic aspects, the circuitry includes a selector switch 71 forchanging the operation of the projector between a coninuous (run ornormal) picture projection mode to a pulse sequence projection mode ofthe solenoid 37, and a potentiometer 72 forming part of an electroniccircuit system 73 operable in stepless, i.e., continuous increments, inconjunction with the commutator switch (referred to also hereinafter asthe shutter shaft switch) by way of the input leads 57 and 58, forcontrolling the pulse mode operation of the solenoid 37 to produce thesequence projection, namely, a slow series of automatically changingstill projections and for varying by such continuous increments theintervals or time spacing of the still projections in such automaticallychanging series of still pro jections.

Referring more in detail to FIG. 6, a transformer 74 has an outputchangeable between 25 volts and 6.5 volts AC as indicated in thedrawing. When mode selector switch 71 is in the 25 volts position (shownin full lines in the figure) the 25 volts RMS output is full waverectified by rectifier 75 to 35 volts DC, unregulated. In thispositioning of the selector switch, the electronic circuit system 73 isin connected operative condition as shown. The rectified 35 volts DC isisolated from a H 5 volts power regulated and supplied by means of adiode 76, zener 77 and resistor 78. The 15 volt DC supply is used toprovide biasing for the operation of unijunction transistor 79, the timeinterval of which is determined by the potentiometer 72, resistor 80 andcapacitor 81. Resistor 82 provides temperature compensation. Resistor 83is used to provide the synchronization signal from the commutator on thecam shaft. Capacitor 84 filters the 35 volt DC supply. Capacitor 85filters the 15 volt DC supply. Resistor 86 limits the current from thedischarge of capacitor 81 and also provides a voltage output to triggera power pulser 87.

The power pulser 87 is a known integrated circuit designed to switchhigh power loads from a precisely timed interval when triggered by alogic level input. It is capable of driving inductive and resistiveloads. PNP transistors 89 coupling the input circuit 90 and the outputcircuit within the device provides isolation which permits considerableflexibility in output circuit configuration and minimizes noise couplingto the input. The rate of change of output voltage is controlled tominimize RFI. A built-in diode 92 facilitates clamping induction loadswhen the output pulse is terminated. The emitter, clamp, collector andinhibit terminals are indicated by the reference characters 93, 94, 95and 96, respectively.

As indicated above, when the mode selector switch 71 is in the 25 voltsRMSposition, the electronic circuit system 73 is in connected operativecondition. When the selector switch 71 is moved to engage contact 97,and in conjunction'therewith a switch 98 is moved by the mechanicalconnection 99 to engage contact 100, the lower 6.5 AC RMS voltage isrectified by rectifier 75 providing approximately 7.5 volt DC which isdirectly applied by way of conductors 101 and 102 to the terminals 103and 104 of the solenoid 37 to operate the same for the normal or runmode of the projector; and the electronic circuit system is at the sametime disconnected from operative condition.

FIGS. 7a and 7b jointly illustrate graphically the theory of operationof the electronic system of the projector. As illustrated, the ordinatesof the graph plots voltage and time of the system. The upper part of thegraph, extending from 10 volts to 15 volts depicts the successive frameperiods, A representing one period per film frame. The frame period maybe varied in terms of time by means of a rheostat motor control (notshown). Different rheostat operated shutter shaft rotational speeds arerepresented by the arrows D. It will be understood that any number ofspeeds may be used by adjustment of the rheostat. Two different speedsonly are indicated for simplicity.

B represents the time elapsed for the voltage from the timingcircuitryto reach a 6 volt level. The time is controlled by the variableresistance of the potentiometer 72; the less the resistance the fasterthe time rise. The

resistor is in series with the resistor 80; their sum in combinationwith capacitor 81 controls the rise time.

It can be seen from FIGS. 7a and 7b that relatively short electricalpulses are creatable at every closure of the commutator or shutter shaftswitch. The magnitude of the pulses, as shown, is substantiallyone-third of the full voltage (15 volts), and is also negative-going indirection. The firing voltage of unijunction transistor 79 isapproximately 60 percent (Eta) of the voltage (15 volts), applied toBase 2 thereof or 9 volts DC as indicated in the graph. Upon each andevery negative pulse, the Base (B2) voltage is lowered by one-third; andthe firing point of the unijunction is also lowered by one-third to theindicated value of 6 volts DC.

Voltages from the timing circuit of the electronic system to the emitterof the unijunction transistor as it rises to the 9 volt level is shownin the lowermost portion of the graph indicated by the rising curves F,F. B represents the periodicity of the rise time for different settingsof the resistance of the potentiometer 72. Several rise time conditionsare shown, each different con dition being illustrated by the appliednumerals 7, 8, 5 etc. C refers to time, and every time interval can haveany number of discharge pulses E,E depending on how long the resistanceof the potentiometer is allowed to remain in a fixed position. Thedrawing illustrates three and two discharge pulses for every time C.

The voltage applied to Base 2 of the unijunction transistor is reducedat the rate of once per revolution of the shutter (cam) shaft. Thisevent occurs only once per revolution irrespective of the shutter shaftspeed. A change of shutter shaft speed results in a change of rate interms of time of these events. The rate of pulsing due to the timingelements of the circuitry is unaffected by a change in shutter speed.The single frame advance occurs only after the voltage from the timingcircuit to the emitter of the unijunction transistor is equal to orexceeds the 6 volt level. When this condition of coincidence occurs, adischarge E pulse is fed to the Power Pulsar which in turn momentarilyactivates the solenoid 37.

The operation of the projector for producing the different sequences ofpicture projection thereof can thus be explained by reference to thegraph of FIGS. 7a and 7b, viewing the same from left to right. In aselected position of the resistances of the potentiomer 72, held in thatposition for a given time, three successive discharge pulses E areproduced in the first C space, each effective for actuating the solenoid37 momentarily; and the result is that a very low projection speedsequence is obtained in which the projected films are spaced sevenframes apart. In the succeeding C space, a different held magnitude ofthe potentiometer resistance produces two discharge pulses E, with theresult of further reducing the sequence" projection speed, in which theprojected films are spaced eight frames apart. In the third C space,with a held change in the magnitude of said resistance, three dischargepulses E are produced, thereby increasing the projection sequence speedin which the projected films are spaced five frames apart. In thesucceeding C spaces, the speed of the motor has been reduced, and at itsreduced speed, the potentiometer resistance has been changed, and heldat each change, to produce the three different sequences of projectionin which the projected films are spaced respectively, eight, five andthree frames apart.

The overall operation of the motion picture projector combination may bedescribed by reference to FIGS. 1, 4, 5, 6 and 7a.

A. Having reference first to FIG. 1, the projector includes a filmtransport means 10, operating means comprising earns 20 and 7 therefor,and a shutter 6 operable in a fixed cyclic movement relation to the filmtransport means, the film transport means being operable by itsoperating means at a normal rate of operation such as to producecontinuous motion picture projection, and mechanism operative forcontrolling the operation of the film transport means for selectivelychanging the rate of operation of the film transport means, withoutaltering said fixed cyclic relation, from its normal rate of producing acontinuous projection of an operated film to a sequence projection,namely a slow series of automatically changing projections.

B. The said mechanism includes an operated device, namely a solenoid 37and its armature actuated shoe 41 connected to a controlled electriccircuit deriving its source from a 6 volt connection of the transformer74 (FIG. 6) for energizing said solenoid to elevate its armature shoe toa set non-intercepting position (FIG. 1) to permit an uninterruptedoperation of the film transport means, for producing the normal rate ofpicture projection.

C. The said mechanism comprises an electronic circuit system generallydesignated as 73 for operating the solenoid 37 to selectively changeitsoperation and its rate of operation and therefore of the film transportmeans without altering its fixed cyclic relation relative to the shutter6, from its aforesaid normal rate of producing continuous filmprojection to a sequence projection. The electronic circuit systemincludes a device, namely a potentiometer 72 for varying by stepless,i.e., continuous, increments the time intervals between the stillprojections of a sequence projection. More specifically, the electroniccircuit system 73 is selectively operable for actuating the solenoiddevice 37 to control its rate of operation, i.e., its rate ofinterception and releasing by the solenoid shoe 41 of the film transportmeans 10 for producing the sequence of still projections.

Thus the solenoid device 37 which is connected to the electronic circuitsystem 73 (FIG. 6), when energized and de-energized by the electroniccircuit system is actuatable between set (the up) and reset (the down)positions respectively to produce successive uninterrupted andinterrupted operations respectively of the film transport means.

D. The projector further includes a switch means, namely switchingelements 51, 52 and 53 (FIGS. 4 and 5), operably connected in fixedcyclic movement to the operating means of said film transport means,said switch being connected in circuit to the electronic circuit system72 by way of the leads 57, 58. The said switch means provides a contact(with the pin 5!) acting as a momentary contact in each of its cyclicmove ments such as to permit single frame advances (A) in the sequencefilm projections as portrayed in FIG. 70.

E. The electronic circuit system 73 comprises electronic elementsdepicted in FIG. 6 for operating the unijunction transistor 83 forcreating electrical pulses F, E (FIG. 7a) active on said solenoid device37 to operate it for producing the film projection sequence orsequences. Thus the electronic circuit system includes means, namely thecircuit of potentiometer 72 for varying by stepless, i.e., continuous,increments the creating of short electrical pulses operating on thesolenoid 37 to vary the rate of intercepting and releasing of the filmtransport means 10.

F. The combination of the motion picture projector elements and theelectronic circuit system provides the following structural andelectrical components:

a. A switch which provides a contact acting as a mo-- tion and theintercepting action, respectively, of

the film transport means 10; and

c. Means, namely the circuit of the potentiometer 72 for varying thetimes of the rise phases of said pulses and for producing the dropphases of said pulses, the momentary contact switch (51, 52, 53)determining the times of the drop phases of said pulses.

It will be apparent that many changes may be made in the structure andrelations of the disclosed features and parts of the motion pictureprojector of the invention without departing from the spirit of theinvention as defined in the following claims.

We claim:

l. A motion picture projector including a film transport means, the filmtransport means being operable at a normal rate of operation such as toproduce continuous motion picture projection, and mechanism forselectively changing the rate of operation of said film transport meansfrom the normal rate of continuous projection to a sequence projection,namely a slow series of automatically changing still projections, saidmechanism comprising an electrically operable device operative forintercepting and releasing said film transport means to prevent andpermit respectively its engagement with the film, an electronic circuitsystem connected to said device selectively operable for actuating saiddevice to control its rate of interception and releasing of the filmtransport means and for producing a pulse sequence projection, theelectronic circuit system including a means for varying by stepless,i.e., continuous increments, the time intervals between the stillprojections produced in said pulse sequence projection, and a switchmechanically connected in cyclic timed relation to the operation of saidfilm transport means, said switch being connected in circuit to theelectronic circuit system and cooperating therewith to provide amomentary contact in each of its cyclic movements for controlling thepulse mode operation of said device in producing the sequenceprojection.

2. The motion picture projector of claim 1, in which the electroniccircuit system includes means for creating electrical pulses active onsaid device, said last recited means including means for producing arise phase in said pulses to charge points to energize said device andfor producing a drop phase of said pulses to discharge points tode-energize said device, deenergization and energization of said deviceeffecting the intercepting and releasing action of the film transportmeans.

3. The motion picture projector of claim 2, in which the electroniccircuit system further includes means for varying the times of the risephases of said pulses.

4. The motion picture projector of claim 3, in which the momentarycontact switch mechanically connected to operate in timed relation tothe operation of the film transport means is connected electrically tosaid electronic circuit system for determining the times of the dropphases of said pulses.

5. The motion picture projector of claim 1, in which an electric circuitis provided connected to said device for energizing said device for anindeterminate period to a condition to permit uninterrupted normaloperation of the film transport means.

6. The motion picture projector of claim 1, in which the electroniccircuit system includes means for creat ing short electrical pulsesactive on said device to operate it rapidly for producing its filmtransport means intercepting and releasing conditions, and the saidswitch provides its momentary contacts for controlling the pulse modeoperation of said device.

7. The motion picture projector of claim 1, in which said switch isoperably connected in fixed cyclic move ment to the operation of saidfilm transport means.

8. The motion picture projector of claim 1, in which said device whencircuit de-energized is movable to a re-set position for interceptingthe film transport means to effect interrupted operations of the filmtransport means.

9. The motion picture projector of claim 1, in which said devicecomprises a solenoid and its armature, the armature being an elementmovable with reference to the film transport means to effect the filmtransport intercepting and releasing actions.

10. The motion picture projector of claim 1, which includes a shutteroperable in a fixed cyclic movement relation to the film transportmeans, and in which said switch includes a commutator fixed to the shaftof the shutter.

* i i i

1. A motion picture projector including a film transport means, the filmtransport means being operable at a normal rate of operation such as toproduce continuous motion picture projection, and mechanism forselectively changing the rate of operation of said film transport meansfrom the normal rate of continuous projection to a ''''sequence''''projection, namely a slow series of automatically changing stillprojections, said mechanism comprising an electrically operable deviceoperative for intercepting and releasing said film transport meaNs toprevent and permit respectively its engagement with the film, anelectronic circuit system connected to said device selectively operablefor actuating said device to control its rate of interception andreleasing of the film transport means and for producing a pulse''''sequence'''' projection, the electronic circuit system including ameans for varying by stepless, i.e., continuous increments, the timeintervals between the still projections produced in said pulse sequenceprojection, and a switch mechanically connected in cyclic timed relationto the operation of said film transport means, said switch beingconnected in circuit to the electronic circuit system and cooperatingtherewith to provide a momentary contact in each of its cyclic movementsfor controlling the pulse mode operation of said device in producing thesequence projection.
 2. The motion picture projector of claim 1, inwhich the electronic circuit system includes means for creatingelectrical pulses active on said device, said last recited meansincluding means for producing a rise phase in said pulses to chargepoints to energize said device and for producing a drop phase of saidpulses to discharge points to de-energize said device, de-energizationand energization of said device effecting the intercepting and releasingaction of the film transport means.
 3. The motion picture projector ofclaim 2, in which the electronic circuit system further includes meansfor varying the times of the rise phases of said pulses.
 4. The motionpicture projector of claim 3, in which the momentary contact switchmechanically connected to operate in timed relation to the operation ofthe film transport means is connected electrically to said electroniccircuit system for determining the times of the drop phases of saidpulses.
 5. The motion picture projector of claim 1, in which an electriccircuit is provided connected to said device for energizing said devicefor an indeterminate period to a condition to permit uninterruptednormal operation of the film transport means.
 6. The motion pictureprojector of claim 1, in which the electronic circuit system includesmeans for creating short electrical pulses active on said device tooperate it rapidly for producing its film transport means interceptingand releasing conditions, and the said switch provides its momentarycontacts for controlling the pulse mode operation of said device.
 7. Themotion picture projector of claim 1, in which said switch is operablyconnected in fixed cyclic movement to the operation of said filmtransport means.
 8. The motion picture projector of claim 1, in whichsaid device when circuit de-energized is movable to a re-set positionfor intercepting the film transport means to effect interruptedoperations of the film transport means.
 9. The motion picture projectorof claim 1, in which said device comprises a solenoid and its armature,the armature being an element movable with reference to the filmtransport means to effect the film transport intercepting and releasingactions.
 10. The motion picture projector of claim 1, which includes ashutter operable in a fixed cyclic movement relation to the filmtransport means, and in which said switch includes a commutator fixed tothe shaft of the shutter.